Mitochondrial biogenesis is an important process in the life cycle of African trypanosomes, occurring during their differentiation from bloodstream to procyclic trypomastigotes. The principal investigator seeks to understand this process, at the molecular and biochemical levels by exploring the molecular events that occur during mitochondrial biogenesis in African trypanosomes and their control. What coordinated expression occurs between mitochondrial and nuclear DNA genes during their transcription and translation? When does translation of these transcripts begin? What molecular mechanisms apply? The hypothesis proposed is that the development of a cyanide-sensitive electron transport system occurs as a result of the triggering of molecular control mechanisms during mitochondrial biogenesis. The identification of the regulatory steps involved will provide some clarification of the molecular events which occur during mitochondrial biogenesis in these organisms. In these studies, the specific aims will be: (1) to characterize the apocytochrome c gene with respect to its nucleotide sequence, expression, and regulation during mitochondrial biogenesis; (2) to purify and sequence the apocytochrome b protein and determine its transcription and translation products during mitochondrial biogenesis; (3) and to purify the glycerol 3-phosphate oxidase, identify and sequence its nuclear-encoded gene, and examine its regulation. The role of the nuclear and mitochondrial DNA during the biosynthesis of the mitochondrial electron transport system is important. More research at the molecular level on the factors which influence transcription and translation of nuclear and mitochondrial genes will hopefully provide clues to the regulation of mitochondrial biogenesis in these organisms and valuable information on how selected genes are regulated.